Business and consumers use a wide variety of fixed and mobile wireless terminals, including cell phones, pagers, Personal Communication Services (PCS) systems, and fixed wireless access devices (i.e., vending machine with cellular capability). Wireless service providers continually try to create new markets for wireless devices and expand existing markets by making wireless devices and services cheaper and more reliable. To attract new customers, wireless service providers implement new services, especially digital data services that, for example, enable a user to browse the Internet or send and receive e-mail.
Code division multiple access (CDMA) technology is used in a variety of wireless networks, including wireless networks that comply with the 1xEV-DV standard. In a CDMA network, mobile stations (e.g., pagers, cell phones, laptop PCs with wireless modems) and base stations transmit and receive data in assigned channels that correspond to specific unique codes. For example, a mobile station may receive forward channel data signals from a base station that are convolutionally coded, formatted, interleaved, spread with a Walsh code and a long pseudo-noise (PN) sequence. In another example, a base station may receive reverse channel data signals from the mobile station that are convolutionally encoded, block interleaved, and spread prior to transmission by the mobile station. The data symbols following interleaving may be separated into an in-phase (I) data stream and a quadrature (Q) data stream for QPSK modulation of an RF carrier. One such implementation is found in the 1xEV-DV version of the IS-2000 standard.
A 1xEV-DV wireless network supports both voice service and data service, such as packet data service. In a 1xEV-DV wireless network, two types of interference limit the performance of the forward link (i.e., transmission link from base station to mobile station). When the mobile station is close to the base station, same cell interference due to multi-path reflections is the predominant type of interference. When the mobile station is at the outer edge of the cell site, neighboring cell interference is the predominant type of interference. Same cell interference is directly related to the transmit power of the base station. Since a 1xEV-DV base station continuously transmits at maximum power for packet data users, same cell interference may be extreme in a 1xEV-DV wireless network. Unfortunately, due to a number of constraints, conventional 1xEV-DV mobile stations do not implement any of the known interference cancellation techniques. As a result, 1xEV-DV cells typically maintain a maximum of only three or four voice calls while maintaining data sessions.
A conventional 1xEV-DV wireless network uses a fixed division of power between data users and voice users that is determined by network operator policy. In an exemplary implementation, a base transceiver station (BTS) first satisfies the power requirements of the voice users and then allocates the remaining power to the data users. The problem with this method is that a single voice user can dictate the data power allocation requirements and therefore throttle the data throughput. This is somewhat illogical, since data users typically pay higher rates than voice-only users.
In another exemplary implementation, the voice power level and the data power level are pre-allocated, whether or not there are active users of each service. This is not an optimal situation, since data users will not experience high throughput even in a cell with few or no voice users. On the other hand, if a cell carries a number of voice users and data users and the interference increases such that the voice users require more power than the pre-allocated power level, the BTS may randomly drop voice calls, or even ALL the voice calls, because the BTS may not be able to determine which voice user to drop in order to maintain the power allocation.
Therefore, there is a need in the art for an improved 1x EV-DV wireless networks. In particular, there is a need for a 1xEV-DV wireless network that is capable of dynamically allocating power in the forward channel between voice users and data users.